Hair dyes and contraceptives have both been linked to breast cancer before, but new research has added additional depth to the evidence.
A recent study led by the Finnish Cancer Registry and researcher Sanna Heikkinen relied on data culled from 8,000 breast cancer patients, as well as 20,000 patients used as controls. The data was collected in survey form, and was self-reported.
They found that women who changed their hair color on a regular basis had a 23% increased risk of breast cancer compared to women who did not dye their hair at all. About a third of women regularly color their hair.
Other studies have also found that women who dye their hair have an increased risk for bladder cancer, brain cancer, and leukemia. One theory is that chemicals in permanent hair dye interacts poorly with air pollutants and leads to tumors.
As for contraception, the study found that using a hormonal intrauterine device (IUD) was linked to a 52% increased risk of breast cancer in post-menopausal women, compared to women who used a copper IUD.
Other hormonal contraceptives, such as the combined pill, were linked to a 32% increased risk in women under 50, compared to women who didn’t use any type of hormonal contraceptive.
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Heikkinen emphasizes that there are other, far riskier factors to be worried about. “The biggest risk factor in breast cancer is high age, and known lifestyle-related risk factors include late age at first birth, small number of children, high alcohol consumption, and sedentary lifestyle,” she said.
In addition, despite some scattered studies on hair dye over the years, an exhaustive review of risk factors done by Cancer Australia has hair dye listed as an “unproven” risk factor. Progesterone-only contraception is also listed as “unproven.”
Of the Finnish study, Dr. Jasmine Just, a health information officer from Cancer Research UK, said: “There’s no convincing evidence that women who use hair dyes are at an increased risk of breast cancer. But, there is clear evidence that the risk of breast cancer can be reduced through things like keeping a healthy weight, being more active and cutting down on alcohol.”Whizzco